In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating current of radio frequency, that is, current with a frequency high enough that their wave nature are taken into account. Transmission lines are used for purposes such as connecting radio transmitter and receivers with their antennas, distributing cable television signals, and computer network connections. Transmission lines use techniques, such as precise conductor dimensions and spacing, and impedance matching, to carry electromagnetic signals with minimal reflections and power losses. Types of transmission lines include twin-lead cables, coaxial cables, striplines, optical fibers, and waveguides, for example.